Fire detector



Jan. 2, 194. R. c. TOWN: 2,185,361.

FIRE DETECTOR Filed Aug. 26, 1956 I jlcpl'.

BELL LIGHT SIREN WITNESS OR mam. MM

ATTORNEYS v Patented Jan. 2, 1940 UNITED STATES PATENT OFFICE 2 Claim.

This invention relates to apparatus adapted for automatic detection ofconditions produced by fire and has for its object the provision ofmeans which will give notice as promptly as posl sible after a firecondition has begun, that such a condition exists. The invention isillustrated in the accompanyingdrawing in which Fig. l is a plan view ofthe apparatus partially in section with the circuits and electricalconnections shown diagrammatically. Fig. 2 is a longitudinal section ofthe air and smoke passage portion of the apparatus and Fig. 3 is a sideelevation of the parts of the apparatus shown in Fig. 2.

The apparatus illustrated in the drawing is one 15 which is adapted tobe placed in any convenient position in any room, building, or storagespace. It consists of apparatus which includes the funnel-shaped airduct A and within which is supported the fan B. The upper end of thetunnelw shaped air ductA communicates with the chamber C bounded bytransparent discs D preferably constituted of quartz glass. The chamber0 communicates at its upper portion with an exhaust duct F equipped withbaffle plates G. The funcgg tion of these plates G is to retard smokewhen present and to cause such smoke to move turbulently in the interiorof the chamber C before being forced through the exhaust. On either sideof the chamber}? are the oonically shaped shields w J and K. Theshield Jsupports the lamp socket which carries thelamp H. The shield K supportsa photo-electric cell E, said cell in turn controlling the relay R. andsaid relay in turn being effectlve to operate one or more signals asindicated 35 diagrammatically at "bell, light", and siren". The electricconnections are as follows: A plug P, insertable in a convenientlylocated outlet, supplies electric current to the lamp and fan andwhenever the thermostat T or the relay R. is op- 40 erated, suppliescurrent to operate the bell,

light, and siren" signals.

A thermostat T is arranged to close an electric switch when thetemperature in its vicinity exceeds a predetermined temperature. Therelay w R under the control of the cell E prevents electric current fromflowing through the branch lines L and L so long as thercell E isaffected by the light from the lamp H, but to close said electriccircuit when effective projection of light from the w lamp H to the cellE is interrupted. As the apparatus is set up and the switches to thelamp,

and to the fan motor areclosed, the fan draws air through the funnel A,the chamber C, and out through the exhaust pipe F. The beam of is thelamp H is directed against the cell E and the switch controlled by therelay R. is open as is also the switch controlled by the thermostat T.

These being the normal conditions of the system, let us suppose that afire condition comes into existence in the vicinity of the apparatus. IAn early manifestation of such a fire condition is frequently thegeneration of smoke and such smoke will be drawn through the inletfunnel A and will cloud the chamber C, the clouding being accentuated bythe effect of the baflles G. 10 This clouding, of the chamber Cinterferes with the clear projection of the rays from the lamp H to thecell E and causes the cell E to cease to ailect the magnet of the relayR. As soon as the relay magnet is deenerglzed its spring moves ll itsarmat re to close a switch so that an electric circuit is at onceestablished via lines L and L to the bell, light, and siren signalswhich are located at convenient points so that a watch- I heat will beat once communicated to the thermostat T and the thermostat switch willat once close the circuit to the bell", light", and siren stations.

Should the lamp H burn out, of fail, or its fuse a 'blow out,-thearrangement is such that when any of such events occur, the lamp willcease to illuminate the cell E with the result that the signal meanswill also beactuated. but in this case the watchman or inspector orother person who responds to the signal will find that a necessaryrepair or replacement was the occasion for the signal and not a firecondition.

The reason why it is suggested that the transparent discs D shouldpreferably be constituted of a quartz glass is that the radiation fromtungsten filament sources consists largely of infra red or heat rayswhich quartz glass intercepts, thereby preventing the heat rays fromreaching the cell. Acc'ordingly, while quartz glass is not absolutelynecessary, its use is desirable.

The apparatus can be very readily installed, is automatic in itsoperation, and requires no attendance. In providing a smoke detectorwhich will give immediate warning when the fire has I l only juststarted, it affords an opportunity for extinguishing the fire before itis out of control. The casing of the apparatus proper may be of anysuitable material, preferably sheet metal.

It isapparent that many modifications with respect to details ofconstruction can be made without departing from the scope of theinven- 1. The combination 01' a casing provided with an intakeduct andan exhaust duct forming-a means of ingress and egress, respectively,through said casing, said casing being closed at each end ."by a wall oflight permeable material and'together with said walls forming anenlarged chamber, a fan disposed in said intake duct for drawing air,and smoke when present in such air, through said duct and forcing suchmixture into the chamber, means disposed in said outlet duct forretarding the escape of the gaseous mixture from the chamber to producea greater concentration of smoke than is present at that time in theatmosphere and to cause the gaseous mixture to move turbulently withinthe chamber, a source of light and light-sensitive means arranged on Wopposite sides 01 the chamber so that beams from said light source passthrough the two end walls and the chamber tmsaid light-sensitive means,and housing members connected to said casing and enclosing said lightsource and light-sensitive means.

2. The combination 01' a cylindrically-shaped casing, the flat ends ofwhich are constituted of walls of light permeable material and theannular portion of which is provided with an intake duct and exhaustduct forming a means or ingress and egress, respectively, through suchannular portion of the casing, means disposed in said inlet duct fordrawing air, and smoke when present in said air, through said inlet ductand forcing such gaseous mixture into said casing, bailies contained insaid exhaust duct to produce a greater concentration of smoke in saidcasing than is present at that time in the atmosphere and together withsaid cylindrically-shaped casing to cause the gaseous mixture to moveturbulently within said casing, a source of light positioned exteriorlyof said casing and arranged to throwlight beams through said walls oflightpermeable material and the interior of said-casingandlight-sensitive means positioned exterior-' 1y on the opposite side ofsaid casing and arranged to receive the light beams passing through thecasing from said light source.

RALPH C. TOWNE.

